One known antenna assembly is disclosed in British Published Patent Application No. GB2473676A and corresponding U.S. application Ser. No. 12/887,220 filed 21 Sep. 2010, the disclosures of which are hereby incorporated by reference. In this known assembly, a dielectrically loaded helical antenna with a solid insulative dielectric core has a coaxial feeder which passes through a passage in the core on a central axis of the antenna. Plated on an outer cylindrical surface of the core are four helical antenna elements and a balun sleeve. An end surface of the core adjacent the balun sleeve is also plated and serves to connect the balun sleeve to the outer conductor of the feeder at the base of the antenna. The connector comprises a central pin soldered to the inner conductor of the feeder, and a hollow outer connection member which encircles the pin and is soldered to the plated end surface of the core so that both the pin and the outer connection member project from the base of the antenna. An insulative moulded covering encases both the antenna and the connector.
In Published International Application No. WO2011/092498, there is disclosed a backfire dielectrically loaded quadrifilar helical antenna in which the feeder is in the form of an elongate laminate board housed in the passage of the core.
It is known to provide a backfire dielectrically loaded helical antenna with an integrated low-noise amplifier. In one example, the antenna is mounted on an end surface of a rectangular plated enclosure, the amplifier comprising a printed circuit board housed in the enclosure and coupled, at one edge, to a coaxial feeder projecting from the base of the antenna and, at an opposite edge, to a coaxial connector mounted on the opposite end of the enclosure. The enclosure has a removable conductive lid. Such an assembly is disclosed in a flysheet issued by Sarantel Limited in May 2003 and entitled “GeoHelix-HTM GPS Antenna”.